1. Field of the Invention
This invention relates generally to a system and method for monitoring automobile operating parameters and for diagnosing operational errors, and more particularly to a system and method for retrieving diagnostic codes from automotive control systems, for monitoring automotive operating parameters, for performing diagnostic inquiries, and for logging and later downloading operational variables.
2. Description of the Related Art
In the field of automotive service, it has become increasingly important to be able to monitor the operation of major automobile systems, such as the engine, transmission and braking system, on a real-time basis for diagnosing and repairing operational problems. Since these major systems are now usually controlled, either entirely or in part, using an microcomputer, the on-board ability of the controllers to store operational information and error codes for later retrieval has been exploited to improve the accuracy with which service personnel diagnose problems. However, these controllers have limited on-board memory for storing these operation parameters. Moreover, relying solely upon on-board capabilities does not allow the service procedures to adapt to information learned after the product has been out in the field for a while. Thus, it is preferable to supplement on-board capabilities with auxiliary diagnostic systems.
One commonly employed auxiliary diagnostic system is commonly known as a "scan tool." The scan tool is typically hand-held and interfaces to the automobiles on-board controllers via the vehicle communication bus, usually tapping in to the bus at a connection point located beneath the dashboard. For a scan tool to be a truly effective aid in diagnosing problems, the scan tool must be able to communicate, or "talk," to the various on-board controllers, regardless of whether the controller is manufactured by the automobile manufacturer or a supplier company.
One disadvantage of currently available scan tools is their inability to accommodate a wide variety of automobile models without requiring substantial hardware or software modification. For most dealerships or service stations, requiring the service technician to stock different scan tools for use on different vehicles is undesirable for reasons of cost, limited storage space and difficulty for the service technician in remembering how to use each of these different scan tools. Most currently available scan tools also rely upon fault trees printed in service manuals for guiding the technician through diagnostic steps. These printed service manuals are costly to prepare and distribute, and become soiled and torn through repeated use. The manner in which these service manuals are supplemented is often problematic, because these manuals are usually bound volumes and do not permit the easy substitution of updated pages.
A concern of service personnel and automobile manufacturers alike is the need to ensure problems are diagnosed accurately and promptly. For the service technician, the customer who brings the vehicle in for service often has a very vague description of the problem ("it makes a clickity noise sometimes") that is not currently manifesting itself when the vehicle is brought in and that the technician finds difficult to recreate. It would be easier for the technician to accurately diagnose the cause of a problem if he can monitor the operating conditions of the vehicle while the problem is manifesting itself. However, this is difficult to achieve because the technician cannot easily drive around with the customer and the customer cannot afford to leave the vehicle with the technician for days at a time. For the technician, it is often expedient to simply replace parts which seem to be the likely culprits in the hopes that the tried-and-true method will solve the problem. However, this increases warranty costs to the manufacturer, because parts that may not be faulty are replaced regardless. Also, when parts are replaced and the problem still remains, the customer become frustrated and often vents this frustration on dealership personnel. Therefore, it would be preferable if tools were provided to the technician which improves his ability to monitoring problems as they occur and to accurately diagnose and repair the cause of the problem. Since scan tools are fairly familiar to technicians, a scan tool which provides these added features would prove very helpful.